2005-12-24 Vesa Jaaskelainen <chaac@nic.fi>

* kern/err.c (grub_error_push): Added new function to support error
stacks.
(grub_error_pop): Likewise.
(grub_error_stack_items): New local variable to support error stacks.
(grub_error_stack_pos): Likewise.
(grub_error_stack_assert): Likewise.
(GRUB_ERROR_STACK_SIZE): Added new define to configure maximum error
stack depth.
(grub_print_error): Added support to print errors from error stack.

* include/grub/err.h (grub_error_push): Added function prototype.
(grub_error_pop): Likewise.

ChangeLog

@@ -1,3 +1,18 @@
+2005-12-24  Vesa Jaaskelainen  <chaac@nic.fi>
+
+	* kern/err.c (grub_error_push): Added new function to support error
+	stacks.
+	(grub_error_pop): Likewise.
+	(grub_error_stack_items): New local variable to support error stacks.
+	(grub_error_stack_pos): Likewise.
+	(grub_error_stack_assert): Likewise.
+	(GRUB_ERROR_STACK_SIZE): Added new define to configure maximum error
+	stack depth.
+	(grub_print_error): Added support to print errors from error stack.
+
+	* include/grub/err.h (grub_error_push): Added function prototype.
+	(grub_error_pop): Likewise.
+
 2005-12-09  Hollis Blanchard  <hollis@penguinppc.org>
 
 	* configure.ac: Accept `powerpc64' as host_cpu.

include/grub/err.h

@@ -1,7 +1,7 @@
 /* err.h - error numbers and prototypes */
 /*
  *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2002,2003,2004  Free Software Foundation, Inc.
+ *  Copyright (C) 2002-2005  Free Software Foundation, Inc.
  *
  *  GRUB is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -60,6 +60,8 @@ extern char EXPORT_VAR(grub_errmsg)[];
 
 grub_err_t EXPORT_FUNC(grub_error) (grub_err_t n, const char *fmt, ...);
 void EXPORT_FUNC(grub_fatal) (const char *fmt, ...) __attribute__ ((noreturn));
+void EXPORT_FUNC(grub_error_push) (void);
+int EXPORT_FUNC(grub_error_pop) (void);
 void EXPORT_FUNC(grub_print_error) (void);
 
 #endif /* ! GRUB_ERR_HEADER */

kern/err.c

@@ -1,7 +1,7 @@
 /* err.c - error handling routines */
 /*
  *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2002  Free Software Foundation, Inc.
+ *  Copyright (C) 2002,2005  Free Software Foundation, Inc.
  *
  *  GRUB is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -22,11 +22,21 @@
 #include <grub/misc.h>
 #include <stdarg.h>
 
-#define GRUB_MAX_ERRMSG	256
+#define GRUB_MAX_ERRMSG		256
+#define GRUB_ERROR_STACK_SIZE	10
 
 grub_err_t grub_errno;
 char grub_errmsg[GRUB_MAX_ERRMSG];
 
+static struct
+{
+  grub_err_t errno;
+  char errmsg[GRUB_MAX_ERRMSG];
+} grub_error_stack_items[GRUB_ERROR_STACK_SIZE];
+
+static int grub_error_stack_pos;
+static int grub_error_stack_assert;
+
 grub_err_t
 grub_error (grub_err_t n, const char *fmt, ...)
 {
@@ -53,9 +63,73 @@ grub_fatal (const char *fmt, ...)
   grub_stop ();
 }
 
+void
+grub_error_push (void)
+{
+  /* Only add items to stack, if there is enough room.  */
+  if (grub_error_stack_pos < GRUB_ERROR_STACK_SIZE)
+    {
+      /* Copy active error message to stack.  */
+      grub_error_stack_items[grub_error_stack_pos].errno = grub_errno;
+      grub_memcpy (grub_error_stack_items[grub_error_stack_pos].errmsg,
+                   grub_errmsg,
+                   sizeof (grub_errmsg));
+        
+      /* Advance to next error stack position.  */
+      grub_error_stack_pos++;
+    }
+  else
+    {
+      /* There is no room for new error message. Discard new error message
+         and mark error stack assertion flag.  */
+      grub_error_stack_assert = 1;
+    }
+
+  /* Allow further operation of other components by resetting
+     active errno to GRUB_ERR_NONE.  */
+  grub_errno = GRUB_ERR_NONE;
+}
+
+int
+grub_error_pop (void)
+{
+  if (grub_error_stack_pos > 0)
+    {
+      /* Pop error message from error stack to current active error.  */
+      grub_error_stack_pos--;
+      
+      grub_errno = grub_error_stack_items[grub_error_stack_pos].errno;
+      grub_memcpy (grub_errmsg,
+                   grub_error_stack_items[grub_error_stack_pos].errmsg,
+                   sizeof (grub_errmsg));
+                  
+      return 1;
+    }
+  else
+    {
+      /* There is no more items on error stack, reset to no error state.  */
+      grub_errno = GRUB_ERR_NONE;
+      
+      return 0;
+    }
+}
+
 void
 grub_print_error (void)
 {
-  if (grub_errno != GRUB_ERR_NONE)
+  /* Print error messages in reverse order. First print active error message
-    grub_printf ("error: %s\n", grub_errmsg);
+     and then empty error stack.  */
+  do
+    {
+      if (grub_errno != GRUB_ERR_NONE)
+        grub_printf ("error: %s\n", grub_errmsg);
+    } 
+  while (grub_error_pop ());
+  
+  /* If there was an assert while using error stack, report about it.  */
+  if (grub_error_stack_assert)
+    {
+      grub_printf ("assert: error stack overflow detected!\n");
+      grub_error_stack_assert = 0;
+    }
 }